FPGA design of low complexity SEFDM detection techniques

This paper presents for the first time the hardware design of low complexity detection algorithms for the recovery of Spectrally Efficient Frequency Division Multiplexing (SEFDM) signals. The work shows that a practical design is feasible using Field Programmable Gate Arrays (FPGAs). Two detection techniques can be implemented using the proposed system architecture, namely Zero Forcing (ZF) and Truncated Singular Value Decomposition (TSVD), demonstrating that our hardware design is flexible. TSVD offers a significant reduction in complexity compared to optimal detection techniques, such as Maximum Likelihood (ML) while outperforming ZF, in terms of Bit Error Rate (BER). Results show excellent fixed-point performance and are comparable to existing floating-point computer-based simulations

Spectrum Optimisation in Wireless Communication Systems: Technology Evaluation, System Design and Practical Implementation

Two key technology enablers for next generation networks are examined in this thesis, namely Cognitive Radio (CR) and Spectrally Efficient Frequency Division Multiplexing (SEFDM). The first part proposes the use of traffic prediction in CR systems to improve the Quality of Service (QoS) for CR users. A framework is presented which allows CR users to capture a frequency slot in an idle licensed channel occupied by primary users. This is achieved by using CR to sense and select target spectrum bands combined with traffic prediction to determine the optimum channel-sensing order. The latter part of this thesis considers the design, practical implementation and performance evaluation of SEFDM. The key challenge that arises in SEFDM is the self-created interference which complicates the design of receiver architectures. Previous work has focused on the development of sophisticated detection algorithms, however, these suffer from an impractical computational complexity. Consequently, the aim of this work is two-fold; first, to reduce the complexity of existing algorithms to make them better-suited for application in the real world; second, to develop hardware prototypes to assess the feasibility of employing SEFDM in practical systems. The impact of oversampling and fixed-point effects on the performance of SEFDM is initially determined, followed by the design and implementation of linear detection techniques using Field Programmable Gate Arrays (FPGAs). The performance of these FPGA based linear receivers is evaluated in terms of throughput, resource utilisation and Bit Error Rate (BER). Finally, variants of the Sphere Decoding (SD) algorithm are investigated to ameliorate the error performance of SEFDM systems with targeted reduction in complexity. The Fixed SD (FSD) algorithm is implemented on a Digital Signal Processor (DSP) to measure its computational complexity. Modified sorting and decomposition strategies are then applied to this FSD algorithm offering trade-offs between execution speed and BER

Cyclostationary signatures for cognitive radio applications and novel multiple access systems

This paper provides a theoretical discussion of two key and ongoing topics in wireless networks, namely spectrum availability and system capacity. Cognitive radio is the current state-of-the-art technology for tackling the former issue. Solutions for the latter topic are usually interference-limited or come at the cost of impractical computational complexity. The use of cyclostationary signatures for OFDM-based systems has recently been suggested to address the aforementioned research challenges

SC-FDMA and OFDMA: The two competing technologies for LTE

One of the key requirements of next generation networks (NGNs) is the support of higher data rates. Although OFDM is capable of delivering the target peak data rates, its high PAPR raises questions as to its suitability in the uplink. SC-FDMA is examined in this paper as a promising alternative to OFDMA. Recent novel techniques offering performance gains are also considered